Micro silicon(mSi)is a promising anode candidate for all-solid-state batteries due to its high specific capacity,low side reactions,and high tap density.However,silicon suffers from its poor electronic and ionic condu...Micro silicon(mSi)is a promising anode candidate for all-solid-state batteries due to its high specific capacity,low side reactions,and high tap density.However,silicon suffers from its poor electronic and ionic conductivity,which is particularly severe on a micro scale and in solid-state systems,leading to increased polarization and inferior electrochemical performance.Doping can broaden the transmission pathways and reduce the diffusion energy barrier for electrons and lithium ions.However,achieving effective,uniform doping in mSi is challenging due to its longer diffusion paths and higher energy barriers.Therefore,current doping research is primarily limited to nanosilicon.In this study,we successfully used a Joule-heating activated staged thermal treatment to achieve full-depth doping of germanium(Ge)in the mSi substrate.The Joule-heating process activated the mSi substrate,resulting in abundant vacancy defects that reduced the diffusion barrier of Ge into the silicon lattice and facilitated full-depth Ge doping.Surprisingly,the resulting Si-Ge anode exhibited significantly enhanced electrical conductivity(70 times).Meanwhile,the improved Li-ion conductivity in mSi and the reduced Young’s modulus enhance the electrode reaction kinetics and integrity after cycling.Ge-doped silicon anodes demonstrate excellent electrochemical performance when applied in sulfide solid-state half-cells and full-cells.This work provides substantial insights into the rational structural design of mSi alloyed anode materials,paving the way for the development of high-performance solid-state Li-ion batteries.展开更多
Lithium?ion batteries(LIBs), which are high?energy?density and low?safety?risk secondary batteries, are underpinned to the rise in electrochemical energy storage devices that satisfy the urgent demands of the global e...Lithium?ion batteries(LIBs), which are high?energy?density and low?safety?risk secondary batteries, are underpinned to the rise in electrochemical energy storage devices that satisfy the urgent demands of the global energy storage market. With the aim of achiev?ing high energy density and fast?charging performance, the exploitation of simple and low?cost approaches for the production of high capacity, high density, high mass loading, and kinetically ion?accessible electrodes that maximize charge storage and transport in LIBs, is a critical need. Toward the construction of high?performance electrodes, carbons are promisingly used in the enhanced roles of active materials, electrochemi?cal reaction frameworks for high?capacity noncarbons, and lightweight current collectors. Here, we review recent advances in the carbon engi?neering of electrodes for excellent electrochemical performance and structural stability, which is enabled by assembled carbon architectures that guarantee su cient charge delivery and volume fluctuation bu ering inside the electrode during cycling. Some specific feasible assem?bly methods, synergism between structural design components of carbon assemblies, and electrochemical performance enhancement are highlighted. The precise design of carbon cages by the assembly of graphene units is potentially useful for the controlled preparation of high?capacity carbon?caged noncarbon anodes with volumetric capacities over 2100 mAh cm^(-3). Finally, insights are given on the prospects and challenges for designing carbon architectures for practical LIBs that simultaneously provide high energy densities(both gravimetric and volumetric) and high rate performance.展开更多
Carbon materials are key components in energy storage and conversion devices and most directly impact device performance.The need for advanced carbon materials has become more pressing with the increasing demand for h...Carbon materials are key components in energy storage and conversion devices and most directly impact device performance.The need for advanced carbon materials has become more pressing with the increasing demand for high-performance energy conversion and storage facilities.Nonetheless,realizing significant performance improvements across devices remains challenging because of the difficulties in controlling irreg-ularly organized microstructures and the specific carbon structures concerned.With the aim of realizing devis-able structures,adjustable functions,and performance breakthroughs,this review proposes the concept of superstructured carbons.In fact,superstructured carbons are a category of carbon-based materials charac-terized by precisely built pores,networks,and interfaces.This unique category meets the particular func-tional demands of high-performance devices and exceeds the rigid structure of traditional carbons.In the context of these superstructured carbons,we present methods for realizing both custom-built structures and target-oriented functionalities.For specific energy-related reactions,we emphasize the targeted property-structure relationships in these well-defined superstructured carbons.Finally,future developments and practi-cability challenges of superstructured carbons are also proposed.展开更多
Aqueous secondary batteries are promising candidates for next-generation large-scale energy storage systems owing to their excellent safety and cost-effectiveness.However,their commercialization faces considerable cha...Aqueous secondary batteries are promising candidates for next-generation large-scale energy storage systems owing to their excellent safety and cost-effectiveness.However,their commercialization faces considerable challenges owing to a limited electrochemical stability window and lower energy density.In this study,we present a rationally designed hydrogel electrolyte,featuring a distinctive polymer network and reduced free water content,created using a UV-curing method.This innovation results in an impressive ionic conductivity of 43 mS cm^(-1),high mechanical strength and an enhanced electrochemical stability window of up to 2.5 V(vs.Zn/Zn^(2+)).The hybrid electrolyte demonstrates impressive viability and versatility,enabling compatibility with various cathode materials for use in both aqueous Na–Zn hybrid batteries and Zn-ion batteries.Notably,when paired with a Prussian blue cathode,the assembled hybrid batteries show remark-able cyclability,enduring over 6000 cycles with a minimal capacity decay of only 0.0096%per cycle at a high current density of 25 C.Additionally,the Zn||Na_(2)MnFe(CN)_(6) full battery using the synthesized hydrogel elec-trolyte achieves a high energy density of approximately 220 Wh kg^(-1) and outstanding rate performance reach-ing up to 5 C.This research provides important insights for designing aqueous hybrid electrolytes that combine both high ionic conductivity and an expansive electrochemical stability window.展开更多
Conventional heterogeneous photocatalysts often suffer from insufficient light absorption,rapid charge recombination,and a lack of specific reactive sites for efficient photocatalytic oxidation.To overcome these limit...Conventional heterogeneous photocatalysts often suffer from insufficient light absorption,rapid charge recombination,and a lack of specific reactive sites for efficient photocatalytic oxidation.To overcome these limitations,we propose a molecular polarization engineering approach utilizing structurally well-defined donor(D)-acceptor(A)covalent triazine frameworks(CTFs).The construction of dipoleinduced built-in electric fields within the D-A-structured CTFs enables enhanced exciton dissociation and facilitates directional charge transfer.Specifically,the asymmetric A_(1)-DA_(2) moiety enhances molecular polarization in the dual-acceptor system CTF-TBT(A_(1)-D-A_(2)),enabling efficient charge separation through multiple electron-withdrawing units.This structural design promotes directional electron transfer toward the secondary acceptor(benzothiazole,A_(2)),while simultaneously concentrating holes on the donor unit.Consequently,the A_(2) moiety acts as a site for efficient O_(2) activation via electron accumulation,whereas the highly oxidized donor unit provides strongly positive holes(h^(+))that facilitate substrate oxidation.Experimental and DFT calculation results confirm that CTF-TBT demonstrates highly enhanced photocatalytic oxidation performance,which can be attributed to its multi-channel charge separation mechanism and spatially separated redox-active sites.This study highlights the effectiveness of molecular dipole engineering in designing heterogeneous photocatalysts with controlled charge transfer pathways and improved redox capabilities.The proposed design principles provide a universal approach for promoting solar-driven chemical synthesis applications.展开更多
The development and exploration of high-energy-density battery systems hold significant importance for environmental protection and sustainable development [1,2]. Sodium-chlorine(Na/Cl_(2)) batteries, derived from thi...The development and exploration of high-energy-density battery systems hold significant importance for environmental protection and sustainable development [1,2]. Sodium-chlorine(Na/Cl_(2)) batteries, derived from thionyl chloride(SOCl_(2)) primary battery conversion, have emerged as a breakthrough energy storage technology due to their high theoretical energy density and wide-temperature applicability [3–5].展开更多
Increasing the density and thickness of electrodes is required to maximize the volumetric energy density of lithium-ion batteries for practical applications.However,dense and thick electrodes,especially highmass-conte...Increasing the density and thickness of electrodes is required to maximize the volumetric energy density of lithium-ion batteries for practical applications.However,dense and thick electrodes,especially highmass-content(>50 wt%) silicon anodes,have poor mechanical stability due to the presence of a large number of unstable interfaces between the silicon and conducting components during cycling.Here we report a network of mechanically robust carbon cages produced by the capillary shrinkage of graphene hydrogels that can contain the silicon nanoparticles in the cages and stabilize the silicon/carbon interfaces.In situ transmission electron microscope characterizations including compression and tearing of the structure and lithiation-induced silicon expansion experiments,have provided insight into the excellent confinement and buffering ability of this interface-strengthened graphene-caged silicon nanoparticle anode material.Consequently,a dense and thick silicon anode with reduced thickness fluctuations has been shown to deliver both high volumetric(>1000 mAh cm^-3) and areal(>6 mAh cm^-2)capacities together with excellent cycling capability.展开更多
Dual-doping of carbon,especially the combination of nitrogen and a secondary heteroatom,has been demonstrated efficient to optimize the oxygen reduction reaction(ORR)performance.However,the optimum dual-doping is stil...Dual-doping of carbon,especially the combination of nitrogen and a secondary heteroatom,has been demonstrated efficient to optimize the oxygen reduction reaction(ORR)performance.However,the optimum dual-doping is still not clear due to the lack of strong experimental proofs,which rely on a reliable method to prepare carbon materials that can rule out the interference factors and then emphasize only the doping effects.In this work,an inside-out doping method is reported to prepare carbon submicrotubes(CSTs)as a material to study the principles of designing dual-doping catalysts for ORR.The interference factors including the metal impurities and doping gradient in the bulk phase are excluded,and the doping effects including the structural and chemical variation of carbon are studied.P-doping exhibited a higher pore-forming ability to perforate carbon and a lower doping content,but a higher ORR catalytic activity as compared with S-and B-doped N-CSTs,demonstrating the N,P co-doping is more efficient in making carbon-based catalysts for ORR.First-principle calculations reveal that the edge C situated around the oxidized P site nearby a graphitic N atom is the active site that shows the lowest ORR overpotential comparable to Pt-based catalysts.This study suggests that the catalytic activity of dual-heteroatoms-doped carbons not only depends on the intrinsic chemical bonding between heteroatoms and carbon,but also is affected by the structural variation generated by introducing different atoms,which can be extended to the study of other kinds of functionalization of carbon and potential reactions besides ORR.展开更多
Rational design and tailoring of the structural features of Co-N-C catalysts are urgently required to construct highly efficient bifunctional non-noble metal electrocatalysts for both oxygen evolution reaction(OER)and...Rational design and tailoring of the structural features of Co-N-C catalysts are urgently required to construct highly efficient bifunctional non-noble metal electrocatalysts for both oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Herein,we report a series of carbon-based catalysts with varied structural features,specifically the graphitic degree of carbon,porosity,and the configuration of active sites,and their effects on bifunctional oxygen electrocatalytic reactions.Through the synergistic tuning of these structural factors,the well-tailored Co-N-C catalyst exhibits a high bifunctional electrocatalytic activity,as revealed by a half-wave potential of 0.84 V for ORR and a low overpotential of 420 mV at 10 mA·cm^(−2)for OER.More impressively,the Zn-air battery using the optimum catalyst delivers excellent performance including a peak power density of 125.2 mW·cm_(−2)and a specific capacity of 790.8 mAh·gZn^(−1),as well as stable cycling durability,outperforming the noble metalsbased catalysts.The first-principles calculations reveal that the interlayer interaction between the pyridinic N-doped graphene and the confined Co nanoparticles increases the electronic states of the active C atoms near the Fermi level,thus enhancing the adsorption of the HOO*intermediate and generating superior catalytic activity for bifunctional oxygen electrocatalysis.By comprehensively studying the structural factors of catalysts,the bifunctional catalytic behaviors,the use in a practical Zn-air device,and theoretical simulations,this work may also give inspirations to the design,use,and understanding of other kinds of catalysts.展开更多
In this paper, the bacterial celluloses(BCs) were pyrolysed in nitrogen and then activated by KOH to form a porous three- dimension-network electrode material for supercapacitor applications. Activated pyrolysed bacte...In this paper, the bacterial celluloses(BCs) were pyrolysed in nitrogen and then activated by KOH to form a porous three- dimension-network electrode material for supercapacitor applications. Activated pyrolysed bacterial cellulose(APBC) samples with enlarged specific surface area and enhanced specific capacitances were obtained. In order to optimize electrochemical properties, APBC samples with different alkali-to-carbon ratios of 1, 2 and 3 were tested in two electrodes symmetrical capacitors. The optimized APBC sample holds the highest specific capacitance of 241.8 F/g, and the energy density of which is 5 times higher than that of PBC even at a current density of 5 A/g. This work presents a successful practice of preparing electrode material from environment-friendly biomass, bacterial cellulose.展开更多
Lithium(Li)metal has been regarded as one of the most promising anode materials to meet the urgent requirements for the next-generation high-energy density batteries.However,the practical use of lithium metal anode is...Lithium(Li)metal has been regarded as one of the most promising anode materials to meet the urgent requirements for the next-generation high-energy density batteries.However,the practical use of lithium metal anode is hindered by the uncontrolled growth of Li dendrites,resulting in poor cycling stability and severe safety issues.Herein,vertical graphene(VG)film grown on graphite paper(GP)as an all-carbon current collector was utilized to regulate the uniform Li nucleation and suppress the growth of dendrites.The high surface area VG grown on GP not only reduces the local current density to the uniform electric field but also allows fast ion transport to homogenize the ion gradients,thus regulating the Li deposition to suppress the dendrite growth.The Li deposition can be further guided with the lithiation reaction between graphite paper and Li metal,which helps to increase lithiophilicity and reduce the Li nucleation barrier as well as the overpotential.As a result,the VG film-based anode demonstrates a stable cycling performance at a current density higher than 5mAcm^(-2)in half cells and a small hysteresis of 50mV at 1mAcm^(-2)in symmetric cells.This work provides an efficient strategy for the rational design of highly stable Li metal anodes.展开更多
Electrochemically reducing CO_(2)to ethanol is attractive but suffers from poor selectivity.Tandem catalysis that integrates the activation of CO_(2)to an intermediate using one active site and the subsequent formatio...Electrochemically reducing CO_(2)to ethanol is attractive but suffers from poor selectivity.Tandem catalysis that integrates the activation of CO_(2)to an intermediate using one active site and the subsequent formation of hydrocarbons on the other site offers a promising approach,where the control of the intermediate transfer between different catalytic sites is challenging.We propose an internally self-feeding mechanism that relies on the orientation of the mass transfer in a hierarchical structure and demonstrate it using a one-dimensional(1D)tandem core-shell catalyst.Specifically,the carbon-coated Ni-core(Ni/C)catalyzes the transformation of CO_(2)-to-CO,after which the CO intermediates are guided to diffuse to the carbon-coated Cu-shell(Cu/C)and experience the selective reduction to ethanol,realizing the orientated key intermediate transfer.Results show that the Faradaic efficiency for ethanol was 18.2%at-1 V vs.RHE(V_(RHE))for up to 100 h.The following mechanism study supports the hypothesis that the CO_(2)reduction on Ni/C generates CO,which is further reduced to ethanol on Cu/C sites.Density functional theory calculations suggest a combined effect of the availability of CO intermediate in Ni/C core and the dimerization of key∗CO intermediates,as well as the subsequent proton-electron transfer process on the Cu/C shell.展开更多
Use of the transition-metal single atomsupported by carbon is an innovative technique that enhances the electrocatalytic behavior of the oxygen reduction reaction(ORR)for Zn-air batteries(ZABs).Yet,building such catal...Use of the transition-metal single atomsupported by carbon is an innovative technique that enhances the electrocatalytic behavior of the oxygen reduction reaction(ORR)for Zn-air batteries(ZABs).Yet,building such catalysts with stable and efficient electron/mass transport pathways,as well as high catalytic activity and stability remains a critical challenge.Here,we develop a hierarchically porous biomass carbon to anchor atomically dispersed Co atoms,simultaneously addressing the active sites’emergence and stability,and electron/mass transit.The optimum catalyst achieves fabulous electrocatalytic behavior with a half-wave potential of 0.82 V for ORR.More impressively,the ZAB with its well-tailored catalyst exhibits extraordinary combined performance,including a high zenith power density of 139.89mW·cm^(−2),outstanding specific capacity,and remarkable rate durability.This rational design strategy can be applied to create high-efficiency and inexpensive electrocatalysts for sustainable energy conversion and storage devices.展开更多
Two-dimensional MXene-based film materials as flexible electrodes have been widely studied in wearable microsupercapacitors(MSCs).However,the existence of strong van derWaals interactions leads to serious self-stackin...Two-dimensional MXene-based film materials as flexible electrodes have been widely studied in wearable microsupercapacitors(MSCs).However,the existence of strong van derWaals interactions leads to serious self-stacking ofMXene layers,resulting in poor ionic dynamics and loss of active sites,which causes MXene film electrodes to exhibit low capacitance and poor rate performance in practical studies.To solve this,a frame-structured hybrid film(labeled as CN-MX hybrid film)is constructed by introducing intercalating agents(nanometer g-C_(3)N_(4))into MXene layers.In this unique hybrid film,the g-C_(3)N_(4)nanoparticles rationally occupy the interspace between MXene layers so as to alleviate layer stacking,thus effectively expanding the electrochemically active surface and promoting proton transfer.Synergistic pseudocapacitance inducted by g-C_(3)N_(4)surface groups,consequently,the CN-MX hybrid film electrode achieves an enhanced capacitive capability.In the three-electrode system,this frame-structured film electrode exhibits an ultra-high areal capacitance of 1932.8 mF cm^(−2).The assembled symmetry flexible MSC device based on CN-MX hybrid film can achieve an energy density of 2.28μWh cm^(−2)at 0.075 mW cm^(−2),as well as a superior cyclic stability with 90.4%retention after 700 cycles in alternating 90o bending and releasing states,revealing its potential in practical applications.展开更多
基金financially supported by the National Key Research and Development Program(2022YFE0127400)the National Natural Science Foundation of China(52172040,52202041,and U23B2077)+1 种基金Taishan Scholar Project of Shandong Province(tsqn202211086,ts202208832,tsqnz20221118)the Fundamental Research Funds for the Central Universities(23CX06055A).
文摘Micro silicon(mSi)is a promising anode candidate for all-solid-state batteries due to its high specific capacity,low side reactions,and high tap density.However,silicon suffers from its poor electronic and ionic conductivity,which is particularly severe on a micro scale and in solid-state systems,leading to increased polarization and inferior electrochemical performance.Doping can broaden the transmission pathways and reduce the diffusion energy barrier for electrons and lithium ions.However,achieving effective,uniform doping in mSi is challenging due to its longer diffusion paths and higher energy barriers.Therefore,current doping research is primarily limited to nanosilicon.In this study,we successfully used a Joule-heating activated staged thermal treatment to achieve full-depth doping of germanium(Ge)in the mSi substrate.The Joule-heating process activated the mSi substrate,resulting in abundant vacancy defects that reduced the diffusion barrier of Ge into the silicon lattice and facilitated full-depth Ge doping.Surprisingly,the resulting Si-Ge anode exhibited significantly enhanced electrical conductivity(70 times).Meanwhile,the improved Li-ion conductivity in mSi and the reduced Young’s modulus enhance the electrode reaction kinetics and integrity after cycling.Ge-doped silicon anodes demonstrate excellent electrochemical performance when applied in sulfide solid-state half-cells and full-cells.This work provides substantial insights into the rational structural design of mSi alloyed anode materials,paving the way for the development of high-performance solid-state Li-ion batteries.
基金supported by the National Science Fund for Distinguished Young Scholars of China (No. 51525204)National Key Basic Research Program of China (2014CB932400)the National Natural Science Foundation of China (No. 51872195 and U1401243)
文摘Lithium?ion batteries(LIBs), which are high?energy?density and low?safety?risk secondary batteries, are underpinned to the rise in electrochemical energy storage devices that satisfy the urgent demands of the global energy storage market. With the aim of achiev?ing high energy density and fast?charging performance, the exploitation of simple and low?cost approaches for the production of high capacity, high density, high mass loading, and kinetically ion?accessible electrodes that maximize charge storage and transport in LIBs, is a critical need. Toward the construction of high?performance electrodes, carbons are promisingly used in the enhanced roles of active materials, electrochemi?cal reaction frameworks for high?capacity noncarbons, and lightweight current collectors. Here, we review recent advances in the carbon engi?neering of electrodes for excellent electrochemical performance and structural stability, which is enabled by assembled carbon architectures that guarantee su cient charge delivery and volume fluctuation bu ering inside the electrode during cycling. Some specific feasible assem?bly methods, synergism between structural design components of carbon assemblies, and electrochemical performance enhancement are highlighted. The precise design of carbon cages by the assembly of graphene units is potentially useful for the controlled preparation of high?capacity carbon?caged noncarbon anodes with volumetric capacities over 2100 mAh cm^(-3). Finally, insights are given on the prospects and challenges for designing carbon architectures for practical LIBs that simultaneously provide high energy densities(both gravimetric and volumetric) and high rate performance.
基金supported by the National Basic Research Program of China(2014CB932400)the National Natural Science Foundation of China(Nos.51932005,52022041 and 52172040)Taishan Scholar Project of Shandong Province(No.tsqnz20221118).
文摘Carbon materials are key components in energy storage and conversion devices and most directly impact device performance.The need for advanced carbon materials has become more pressing with the increasing demand for high-performance energy conversion and storage facilities.Nonetheless,realizing significant performance improvements across devices remains challenging because of the difficulties in controlling irreg-ularly organized microstructures and the specific carbon structures concerned.With the aim of realizing devis-able structures,adjustable functions,and performance breakthroughs,this review proposes the concept of superstructured carbons.In fact,superstructured carbons are a category of carbon-based materials charac-terized by precisely built pores,networks,and interfaces.This unique category meets the particular func-tional demands of high-performance devices and exceeds the rigid structure of traditional carbons.In the context of these superstructured carbons,we present methods for realizing both custom-built structures and target-oriented functionalities.For specific energy-related reactions,we emphasize the targeted property-structure relationships in these well-defined superstructured carbons.Finally,future developments and practi-cability challenges of superstructured carbons are also proposed.
基金financially supported by National Key Research and Development Program of China(Grant No.2022YFE0127400)Taishan Scholar Project of Shandong Province(Grant Nos.ts202208832 and tsqnz20221118)+1 种基金National Natural Science Foundation of China(Grant No.52473285)Shandong Provincial Natural Science Foundation(Grant No.21CX06028A).
文摘Aqueous secondary batteries are promising candidates for next-generation large-scale energy storage systems owing to their excellent safety and cost-effectiveness.However,their commercialization faces considerable challenges owing to a limited electrochemical stability window and lower energy density.In this study,we present a rationally designed hydrogel electrolyte,featuring a distinctive polymer network and reduced free water content,created using a UV-curing method.This innovation results in an impressive ionic conductivity of 43 mS cm^(-1),high mechanical strength and an enhanced electrochemical stability window of up to 2.5 V(vs.Zn/Zn^(2+)).The hybrid electrolyte demonstrates impressive viability and versatility,enabling compatibility with various cathode materials for use in both aqueous Na–Zn hybrid batteries and Zn-ion batteries.Notably,when paired with a Prussian blue cathode,the assembled hybrid batteries show remark-able cyclability,enduring over 6000 cycles with a minimal capacity decay of only 0.0096%per cycle at a high current density of 25 C.Additionally,the Zn||Na_(2)MnFe(CN)_(6) full battery using the synthesized hydrogel elec-trolyte achieves a high energy density of approximately 220 Wh kg^(-1) and outstanding rate performance reach-ing up to 5 C.This research provides important insights for designing aqueous hybrid electrolytes that combine both high ionic conductivity and an expansive electrochemical stability window.
基金supported by the National Natural Science Foundation of China (22475238 and 22575268)the Natural Science Foundation of Shandong Province (ZR2024MB136)+1 种基金the Fundamental Research Funds for the Central Universities (25CX02019A and R20220132)the Self-directed Research Project of Shandong Key Laboratory of Intelligent Energy Materials。
文摘Conventional heterogeneous photocatalysts often suffer from insufficient light absorption,rapid charge recombination,and a lack of specific reactive sites for efficient photocatalytic oxidation.To overcome these limitations,we propose a molecular polarization engineering approach utilizing structurally well-defined donor(D)-acceptor(A)covalent triazine frameworks(CTFs).The construction of dipoleinduced built-in electric fields within the D-A-structured CTFs enables enhanced exciton dissociation and facilitates directional charge transfer.Specifically,the asymmetric A_(1)-DA_(2) moiety enhances molecular polarization in the dual-acceptor system CTF-TBT(A_(1)-D-A_(2)),enabling efficient charge separation through multiple electron-withdrawing units.This structural design promotes directional electron transfer toward the secondary acceptor(benzothiazole,A_(2)),while simultaneously concentrating holes on the donor unit.Consequently,the A_(2) moiety acts as a site for efficient O_(2) activation via electron accumulation,whereas the highly oxidized donor unit provides strongly positive holes(h^(+))that facilitate substrate oxidation.Experimental and DFT calculation results confirm that CTF-TBT demonstrates highly enhanced photocatalytic oxidation performance,which can be attributed to its multi-channel charge separation mechanism and spatially separated redox-active sites.This study highlights the effectiveness of molecular dipole engineering in designing heterogeneous photocatalysts with controlled charge transfer pathways and improved redox capabilities.The proposed design principles provide a universal approach for promoting solar-driven chemical synthesis applications.
文摘The development and exploration of high-energy-density battery systems hold significant importance for environmental protection and sustainable development [1,2]. Sodium-chlorine(Na/Cl_(2)) batteries, derived from thionyl chloride(SOCl_(2)) primary battery conversion, have emerged as a breakthrough energy storage technology due to their high theoretical energy density and wide-temperature applicability [3–5].
基金the National Natural Science Foundation of China(51872195)the National Science Fund for Distinguished Young Scholars of China(51525204)+1 种基金JSPS KAKENHI(20K05281)the Beijing Natural Science Foundation(2192061)。
文摘Increasing the density and thickness of electrodes is required to maximize the volumetric energy density of lithium-ion batteries for practical applications.However,dense and thick electrodes,especially highmass-content(>50 wt%) silicon anodes,have poor mechanical stability due to the presence of a large number of unstable interfaces between the silicon and conducting components during cycling.Here we report a network of mechanically robust carbon cages produced by the capillary shrinkage of graphene hydrogels that can contain the silicon nanoparticles in the cages and stabilize the silicon/carbon interfaces.In situ transmission electron microscope characterizations including compression and tearing of the structure and lithiation-induced silicon expansion experiments,have provided insight into the excellent confinement and buffering ability of this interface-strengthened graphene-caged silicon nanoparticle anode material.Consequently,a dense and thick silicon anode with reduced thickness fluctuations has been shown to deliver both high volumetric(>1000 mAh cm^-3) and areal(>6 mAh cm^-2)capacities together with excellent cycling capability.
基金support from the National Natural Science Foundation of China(No.51425302).
文摘Dual-doping of carbon,especially the combination of nitrogen and a secondary heteroatom,has been demonstrated efficient to optimize the oxygen reduction reaction(ORR)performance.However,the optimum dual-doping is still not clear due to the lack of strong experimental proofs,which rely on a reliable method to prepare carbon materials that can rule out the interference factors and then emphasize only the doping effects.In this work,an inside-out doping method is reported to prepare carbon submicrotubes(CSTs)as a material to study the principles of designing dual-doping catalysts for ORR.The interference factors including the metal impurities and doping gradient in the bulk phase are excluded,and the doping effects including the structural and chemical variation of carbon are studied.P-doping exhibited a higher pore-forming ability to perforate carbon and a lower doping content,but a higher ORR catalytic activity as compared with S-and B-doped N-CSTs,demonstrating the N,P co-doping is more efficient in making carbon-based catalysts for ORR.First-principle calculations reveal that the edge C situated around the oxidized P site nearby a graphitic N atom is the active site that shows the lowest ORR overpotential comparable to Pt-based catalysts.This study suggests that the catalytic activity of dual-heteroatoms-doped carbons not only depends on the intrinsic chemical bonding between heteroatoms and carbon,but also is affected by the structural variation generated by introducing different atoms,which can be extended to the study of other kinds of functionalization of carbon and potential reactions besides ORR.
基金the National Natural Science Foundation of China(Nos.51425302,51702062,and U20A20131)the National Key R&D Program of China(No.2021YFA1202802)+1 种基金the China Postdoctoral Science Foundation Funded Project(No.2021M690801)the CAS Pioneer Hundred Talents Program,and the China University of Petroleum(East China).
文摘Rational design and tailoring of the structural features of Co-N-C catalysts are urgently required to construct highly efficient bifunctional non-noble metal electrocatalysts for both oxygen evolution reaction(OER)and oxygen reduction reaction(ORR).Herein,we report a series of carbon-based catalysts with varied structural features,specifically the graphitic degree of carbon,porosity,and the configuration of active sites,and their effects on bifunctional oxygen electrocatalytic reactions.Through the synergistic tuning of these structural factors,the well-tailored Co-N-C catalyst exhibits a high bifunctional electrocatalytic activity,as revealed by a half-wave potential of 0.84 V for ORR and a low overpotential of 420 mV at 10 mA·cm^(−2)for OER.More impressively,the Zn-air battery using the optimum catalyst delivers excellent performance including a peak power density of 125.2 mW·cm_(−2)and a specific capacity of 790.8 mAh·gZn^(−1),as well as stable cycling durability,outperforming the noble metalsbased catalysts.The first-principles calculations reveal that the interlayer interaction between the pyridinic N-doped graphene and the confined Co nanoparticles increases the electronic states of the active C atoms near the Fermi level,thus enhancing the adsorption of the HOO*intermediate and generating superior catalytic activity for bifunctional oxygen electrocatalysis.By comprehensively studying the structural factors of catalysts,the bifunctional catalytic behaviors,the use in a practical Zn-air device,and theoretical simulations,this work may also give inspirations to the design,use,and understanding of other kinds of catalysts.
基金supported by the Ministry of Science and Technology of China (2012CB933403)the National Natural Science Foundation of China (21173057, 51425302)the Chinese Academy of Sciences.
文摘In this paper, the bacterial celluloses(BCs) were pyrolysed in nitrogen and then activated by KOH to form a porous three- dimension-network electrode material for supercapacitor applications. Activated pyrolysed bacterial cellulose(APBC) samples with enlarged specific surface area and enhanced specific capacitances were obtained. In order to optimize electrochemical properties, APBC samples with different alkali-to-carbon ratios of 1, 2 and 3 were tested in two electrodes symmetrical capacitors. The optimized APBC sample holds the highest specific capacitance of 241.8 F/g, and the energy density of which is 5 times higher than that of PBC even at a current density of 5 A/g. This work presents a successful practice of preparing electrode material from environment-friendly biomass, bacterial cellulose.
基金We appreciate support from the National Key Research and Development Program of China(2018YFE0124500 and 2019YFA0705700)the National Natural Science Foundation of China(Nos.51972190 and 51932005)+4 种基金the National Science Fund for Distinguished Young Scholars,China(No.51525204)the Guangdong Natural Science Funds for Distinguished Young Scholars(2017B030306006)the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01N111)the Shenzhen Basic Research Project(Grant Nos.JCYJ20170412171359175 and JCYJ20180508152037520)the Shenzhen Graphene Manufacturing Innovation Center(201901161513 and 201901171523).
文摘Lithium(Li)metal has been regarded as one of the most promising anode materials to meet the urgent requirements for the next-generation high-energy density batteries.However,the practical use of lithium metal anode is hindered by the uncontrolled growth of Li dendrites,resulting in poor cycling stability and severe safety issues.Herein,vertical graphene(VG)film grown on graphite paper(GP)as an all-carbon current collector was utilized to regulate the uniform Li nucleation and suppress the growth of dendrites.The high surface area VG grown on GP not only reduces the local current density to the uniform electric field but also allows fast ion transport to homogenize the ion gradients,thus regulating the Li deposition to suppress the dendrite growth.The Li deposition can be further guided with the lithiation reaction between graphite paper and Li metal,which helps to increase lithiophilicity and reduce the Li nucleation barrier as well as the overpotential.As a result,the VG film-based anode demonstrates a stable cycling performance at a current density higher than 5mAcm^(-2)in half cells and a small hysteresis of 50mV at 1mAcm^(-2)in symmetric cells.This work provides an efficient strategy for the rational design of highly stable Li metal anodes.
基金the National Natural Science Foundation of China(U20A20131 and 51425302)National Key R&D Program of China(2022YFF0712200,2021YFA1202802).
文摘Electrochemically reducing CO_(2)to ethanol is attractive but suffers from poor selectivity.Tandem catalysis that integrates the activation of CO_(2)to an intermediate using one active site and the subsequent formation of hydrocarbons on the other site offers a promising approach,where the control of the intermediate transfer between different catalytic sites is challenging.We propose an internally self-feeding mechanism that relies on the orientation of the mass transfer in a hierarchical structure and demonstrate it using a one-dimensional(1D)tandem core-shell catalyst.Specifically,the carbon-coated Ni-core(Ni/C)catalyzes the transformation of CO_(2)-to-CO,after which the CO intermediates are guided to diffuse to the carbon-coated Cu-shell(Cu/C)and experience the selective reduction to ethanol,realizing the orientated key intermediate transfer.Results show that the Faradaic efficiency for ethanol was 18.2%at-1 V vs.RHE(V_(RHE))for up to 100 h.The following mechanism study supports the hypothesis that the CO_(2)reduction on Ni/C generates CO,which is further reduced to ethanol on Cu/C sites.Density functional theory calculations suggest a combined effect of the availability of CO intermediate in Ni/C core and the dimerization of key∗CO intermediates,as well as the subsequent proton-electron transfer process on the Cu/C shell.
基金This research was made possible by the financial support by the National Natural Science Foundation of Shandong,China(grant nos.ZR2020JQ21 and ZR2021ZD24)the National Natural Science Foundation of China(grant nos.51873231 and 22138013)the Taishan Scholar Project of Shandong,China(grant no.tsqn201909062).
文摘Use of the transition-metal single atomsupported by carbon is an innovative technique that enhances the electrocatalytic behavior of the oxygen reduction reaction(ORR)for Zn-air batteries(ZABs).Yet,building such catalysts with stable and efficient electron/mass transport pathways,as well as high catalytic activity and stability remains a critical challenge.Here,we develop a hierarchically porous biomass carbon to anchor atomically dispersed Co atoms,simultaneously addressing the active sites’emergence and stability,and electron/mass transit.The optimum catalyst achieves fabulous electrocatalytic behavior with a half-wave potential of 0.82 V for ORR.More impressively,the ZAB with its well-tailored catalyst exhibits extraordinary combined performance,including a high zenith power density of 139.89mW·cm^(−2),outstanding specific capacity,and remarkable rate durability.This rational design strategy can be applied to create high-efficiency and inexpensive electrocatalysts for sustainable energy conversion and storage devices.
基金the National Natural Science Foundation of China(grant nos.51877216,52277229,and 22109178)Natural Science Foundation of Shandong Province(grant nos.ZR2020MB078,ZR2021QB085,and ZR2022MB094)+1 种基金National Key Research and Development of China(grant no.2022YFA1503400)Postdoctoral Innovative Talent Support Program of Shandong Province(grant no.SDBX2021005).
文摘Two-dimensional MXene-based film materials as flexible electrodes have been widely studied in wearable microsupercapacitors(MSCs).However,the existence of strong van derWaals interactions leads to serious self-stacking ofMXene layers,resulting in poor ionic dynamics and loss of active sites,which causes MXene film electrodes to exhibit low capacitance and poor rate performance in practical studies.To solve this,a frame-structured hybrid film(labeled as CN-MX hybrid film)is constructed by introducing intercalating agents(nanometer g-C_(3)N_(4))into MXene layers.In this unique hybrid film,the g-C_(3)N_(4)nanoparticles rationally occupy the interspace between MXene layers so as to alleviate layer stacking,thus effectively expanding the electrochemically active surface and promoting proton transfer.Synergistic pseudocapacitance inducted by g-C_(3)N_(4)surface groups,consequently,the CN-MX hybrid film electrode achieves an enhanced capacitive capability.In the three-electrode system,this frame-structured film electrode exhibits an ultra-high areal capacitance of 1932.8 mF cm^(−2).The assembled symmetry flexible MSC device based on CN-MX hybrid film can achieve an energy density of 2.28μWh cm^(−2)at 0.075 mW cm^(−2),as well as a superior cyclic stability with 90.4%retention after 700 cycles in alternating 90o bending and releasing states,revealing its potential in practical applications.
